Previous clinical studies with cancer vaccines have:

C. Not clearly demonstrated induction of tumor-specific immune response.

DISCUSSION: Several different approaches in experimental animal studies in the 1970s formed the basis for human clinical trials of SAI against human cancers. Although several thousand patients have been injected with a variety of tumor cell preparations in this country and elsewhere during the past 25 years, the complexity of the studies has made it difficult to definitively assess the value of this approach to cancer therapy. Nonetheless, a number of clinical trials have suggested a therapeutic benefit of SAI. Most of these trials have two features in common: (1) a therapeutic effect was not seen or, if seen, has not been confirmed independently; and (2) no acceptable information was provided on the presence of tumor antigens in the vaccines and the immune response of patients to these antigens.